The stingless bee Trigona spinipes (Hymenoptera: Apidae) is at risk from a range of insecticides via direct ingestion and trophallactic exchanges

Abstract

BACKGROUNDThe stingless bee, Trigona spinipes, is an important pollinator of numerous native and cultivated plants. Trigona spinipes population can be negatively impacted by insecticides commonly used for pest control in crops. However, this species has been neglected in toxicological studies. Here we observed the effects of seven insecticides on the survival of bees that had fed directly on insecticide‐contaminated food sources or received insecticides via trophallactic exchanges between nestmates. The effects of insecticides on flight behavior were also determined for the compounds considered to be of low toxicity.RESULTSImidacloprid, spinosad, and malathion were categorized as highly toxic to T. spinipes, while lambda‐cyhalothrin, methomyl, and chlorfenapyr were medium to low toxicity and interfered with two aspects of flight behavior evaluated here. Chlorantraniliprole was the only insecticide tested here that had no significant effect on T. spinipes survival, although it did interfere with one aspect of flight capacity. A single bee that had ingested malathion, spinosad, and imidacloprid, could contaminate three, four, and nineteen other bees, respectively via trophallaxis, resulting in the death of the recipients.CONCLUSIONThis is the first study to evaluate the ecotoxicology of a range of insecticides that not only negatively affected T. spinipes survival but also interfered with flight capacity, a very important aspect of pollination behavior. The toxicity of the insecticides was observed following direct ingestion and also via trophallactic exchanges between nestmates, highlighting the possibility of lethal effects of these insecticides spreading throughout the colony, reducing the survival of non‐foraging individuals.This article is protected by copyright. All rights reserved.